JP2012232387A - Device and method for driving main shaft unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for driving a main shaft unit which can prevent the breakage of a main shaft unit for holding a main shaft, and to provide a method for driving a main shaft unit.SOLUTION: A machine tool 100 includes: the main shaft unit including the main shaft for mounting a tool thereto and a main shaft driving motor 133 for rotatably driving the main shaft; a unit moving part including respective shaft motors 211 for moving the main shaft unit relatively to a workpiece; respective torque sensors 220 for detecting each torque of respective shaft motors 211; and a numerical control device 300 for controlling each drive speed of respective shaft motors 211 based on detected torque. The numerical control device 300 includes: a memory storage part 310 for storing a first torque limiting value; a torque monitoring means 341 for comparing torque with each other; and a speed control means 342A which, when the torque monitoring means 341 determines that the detected torque exceeds the first torque limiting value, reduces a drive speed V of the corresponding shaft motor 211.

Description

  The present invention relates to a spindle unit driving device that controls driving when a spindle unit that holds a spindle is moved in a predetermined direction, and a spindle unit driving method.

Conventionally, there is a machine tool that processes a workpiece by rotating a spindle (see, for example, Patent Document 1).
In this machine tool, a processing torque applied to the tool is detected by a torque sensor provided in the tool. Further, a deviation between the torque target value input from the outside and the detected machining torque is obtained, and a feed correction amount is calculated based on this deviation.

JP 7-195256 A

By the way, in the machine tool described in Patent Document 1, there is a torque sensor for detecting the torque applied to the main shaft, and the driving of the main shaft is controlled based on the torque detected by the torque sensor so that the main shaft is attached to the main shaft. It is possible to avoid breakage of the used tool. However, it does not detect torque with respect to the spindle unit that holds the spindle, and the spindle unit cannot be protected.
Here, the fluctuation | variation of the torque which concerns on the unit drive part which moves a spindle unit with respect to a workpiece | work at the time of drilling using the conventional machine tool is shown in FIG. In FIG. 5, (A) is a figure which shows the fluctuation | variation of the torque when the load which concerns on a spindle unit does not exceed a predetermined | prescribed limit value, but drilling is completed as usual. On the other hand, (B) is a figure which shows the fluctuation | variation of the torque when the load concerning a spindle unit increases at the time of drilling.

As shown in FIG. 5, when the spindle unit is driven, if the load on the spindle unit increases, the torque related to the unit drive unit for driving the spindle unit also increases accordingly. If the load on the spindle unit is overloaded, the torque on the unit drive unit also exceeds a predetermined torque limit value, and the spindle unit may be damaged even if the tool is not damaged. is there.
In general, when the tool is damaged and when the spindle unit is damaged, if the tool is damaged, it is only necessary to replace the tool. However, if the spindle unit is damaged, the cost and time required for repair are reduced. Becomes larger. Therefore, a configuration that can effectively prevent damage to the spindle unit including the spindle is desired.

  An object of the present invention is to provide a spindle unit driving device and a spindle unit driving method capable of preventing the spindle unit holding the spindle from being damaged.

  A spindle unit driving apparatus according to the present invention includes a spindle unit including a spindle on which a tool for machining a workpiece is mounted, a spindle drive unit that rotationally drives the spindle, and a unit that moves the spindle unit relative to the workpiece. A moving unit; a torque detecting unit that detects torque applied to the unit moving unit; and a control unit that controls a relative moving speed of the spindle unit with respect to the workpiece based on the detected torque detected by the torque detecting unit; And the control section stores storage means for preventing damage to prevent damage to the spindle unit, and torque comparison means for comparing the detected torque and the torque limit value for preventing damage. When the detected torque exceeds the breakage preventing torque limit value, the spindle with respect to the workpiece by the unit moving unit A speed control means for reducing the relative movement speed of the knitting, characterized by comprising a.

In the present invention, a spindle unit having a spindle and a spindle drive unit, a unit moving unit that moves the spindle unit relative to the workpiece, and a unit moving unit that adds the unit to the unit moving unit when moving the spindle unit. A torque detection unit that detects torque and a control unit that controls movement of the unit moving unit are provided. Then, the control unit compares the detected torque detected by the torque detecting unit with the damage preventing torque limit value stored in the storage means, and when the detected torque exceeds the damage preventing torque limit value, The unit moving unit is controlled so as to reduce the relative moving speed of the spindle unit with respect to the workpiece.
In such a configuration, since the torque detecting unit detects the torque applied to the unit moving unit, it is possible to detect the load applied to the entire main spindle unit including the main shaft. Therefore, by controlling the unit moving unit based on the detected torque detected by such a torque detecting unit, it is possible to effectively prevent damage to the spindle unit due to overload.

  In the spindle unit driving apparatus according to the present invention, the control unit includes a time measuring unit that measures time, and the speed control unit performs predetermined damage prevention from a timing at which the detected torque exceeds the damage preventing torque limit value. It is preferable to reduce the relative movement speed after the breakage dead zone time elapses when the detected torque remains exceeding the breakage prevention torque limit value while the dead zone time has passed.

  According to the present invention, the speed control means controls the unit moving portion after the detected torque exceeds the damage prevention torque limit value and the breakage prevention deadband time elapses, so that the relative speed of the spindle unit to the workpiece is increased. Reduce travel speed. That is, even when the detected torque exceeds the torque limit value for preventing damage, the torque applied to the unit moving unit may decrease before the dead zone time elapses. In such a case, if the relative moving speed of the spindle unit with respect to the workpiece is lowered by the unit moving unit, the time required for machining becomes longer, and the machining work efficiency may be lowered. On the other hand, in the present invention, the speed control means is configured such that when the detected torque remains in excess of the damage prevention torque limit value after the dead zone time for preventing damage, the spindle unit relative to the workpiece. Therefore, a decrease in movement speed due to a temporary load increase can be avoided, and a decrease in work efficiency can be suppressed.

  In the spindle unit driving apparatus according to the present invention, the speed control means may apply the detected torque to the damage prevention torque limit from when the relative movement speed is reduced until a predetermined breakage prevention review time elapses. In the case where the value still exceeds the value, it is preferable that the relative movement speed is further reduced after the breakage prevention review time elapses from the timing when the relative movement speed is reduced.

  In the present invention, the speed control means monitors the detected torque even after the relative movement speed of the spindle unit with respect to the work is reduced, and detects the damage prevention review time from the timing when the relative movement speed is reduced. When the torque exceeds the torque limit value for preventing damage, the relative movement speed is further reduced. That is, the speed control means reduces the relative movement speed until the detected torque falls below the damage prevention torque limit value. As a result, it is possible to reliably set the torque relating to the unit moving portion to be equal to or less than the torque limit value for preventing damage, and to reliably prevent the spindle unit from being damaged.

In the spindle unit driving apparatus of the present invention, it is preferable that the speed control means reduce the relative movement speed at a constant ratio with respect to a reference relative movement speed.
Here, the reference relative movement speed may be, for example, a preset reference relative movement speed, or may be a relative movement speed before the speed change.
According to the present invention, the speed control means reduces the relative movement speed at a constant ratio. That is, the speed control means reduces the relative movement speed when the detected torque is equal to or greater than the torque limit value for preventing breakage. At this time, for example, if the speed is reduced to the minimum speed at once, the work efficiency is significantly reduced. . On the other hand, as described above, by gradually reducing the relative movement speed at a constant ratio, the machining operation can be continued while maintaining the torque applied to the spindle unit at an optimum magnitude, which reduces the work efficiency. Can be suppressed.

  In the spindle unit driving apparatus of the present invention, the storage means stores a movement promotion torque limit value for urging the movement of the spindle unit, and the speed control means has the detected torque as the movement promotion torque limit value. When it is less than the range, it is preferable to increase the relative movement speed.

  In the present invention, when the relative movement speed of the spindle unit with respect to the workpiece is small and the torque (detected torque) related to the unit moving unit is lower than the movement promoting torque limit value, the control unit is Increase movement speed. As described above, when the relative movement speed of the spindle unit with respect to the workpiece is reduced, the work efficiency is reduced. However, by increasing (returning) the relative movement speed as in the present invention, the machining work efficiency is improved. Can be improved.

  In the spindle unit driving apparatus according to the present invention, the control unit includes a time measuring unit that measures time, and the speed control unit is configured to perform predetermined movement promotion from a timing when the detected torque falls below the movement promotion torque limit value. When the detected torque remains below the movement promotion torque limit value while the dead zone time elapses, the relative movement speed is preferably increased after the movement promotion dead zone time has elapsed.

According to the present invention, the speed control means of the control unit controls the unit moving unit after the detected torque exceeds the movement promoting torque limit value and the movement limiting deadband time elapses, and the spindle unit with respect to the workpiece is controlled. Increase relative movement speed.
Here, the control unit may immediately control the unit moving unit to increase the relative moving speed of the spindle unit with respect to the workpiece when the detected torque is lower than the movement promoting torque limit value. However, for example, immediately after the relative speed of the spindle unit with respect to the workpiece is reduced based on the comparison between the detected torque and the torque limit value for preventing breakage, the torque temporarily decreases, but the torque does not increase after the elapse of time. May rise. In this case, if the relative movement speed of the spindle unit with respect to the workpiece is increased at a timing when the detected torque falls below the movement promoting torque, the detected torque may again exceed the damage prevention torque limit value, and speed control is performed again. It is necessary to implement a speed reduction process by means.
On the other hand, in the present invention, by providing the dead zone time for promoting the movement as described above, it is possible to confirm the change in the torque related to the unit moving unit and the spindle unit, and the relative rotation of the spindle unit with respect to the workpiece at an appropriate timing. Speed can be increased.

In the spindle unit driving apparatus of the present invention, it is preferable that the speed control means increases the relative movement speed at a constant rate with respect to a reference relative movement speed.
According to the present invention, the speed control means increases the relative movement speed at a constant rate. That is, the speed control means increases the relative movement speed when the detected torque is equal to or less than the movement promotion torque limit value. Here, for example, after reducing the relative movement speed of the spindle unit to the workpiece based on the torque limit value for preventing damage, the relative torque is returned to the original speed because the detected torque is lower than the movement promotion torque limit value. In such a case, it is conceivable that the detected torque again exceeds the torque limit value for preventing damage. On the other hand, when the relative speed of the spindle unit relative to the workpiece is gradually increased at a constant rate, overloading the spindle unit due to excessive speed increase can be prevented, and the optimum load is applied to the spindle unit. Processing can be continued while maintaining the state.

A spindle unit driving method of the present invention includes a spindle unit including a spindle on which a tool for machining a workpiece is mounted, a spindle drive unit that rotationally drives the spindle, and a unit that moves the spindle unit relative to the workpiece. A moving unit; and a torque detecting unit that detects torque applied to the unit moving unit, and controls the moving speed of the spindle unit in the unit moving unit based on the detected torque detected by the torque detecting unit. A spindle unit driving method, wherein a comparison step for comparing a torque limit value for preventing damage for preventing damage to the spindle unit and the detected torque, and in the comparing step, the detected torque is the torque for preventing damage. When the limit value is exceeded, the spindle unit is relative to the workpiece by the unit moving unit. A speed control step for reducing the moving speed, characterized in that it comprises a.
According to the present invention, similarly to the above-described invention, it is possible to effectively prevent breakage due to an increase in the load on the spindle unit.

The perspective view which shows schematic structure of the machine tool (spindle unit drive device) of one Embodiment which concerns on this invention. The block diagram which shows schematic structure of the machine tool of this embodiment. The flowchart which shows operation | movement of the machine tool of this embodiment. In the machine tool of this embodiment, the figure which shows the relationship between detected torque and time, and the relationship between drive speed and time. The figure which shows the relationship between the torque which concerns on the spindle unit in the conventional machine tool, and time.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.
[Configuration of machine tool]
FIG. 1 is a perspective view showing a schematic configuration of a machine tool that is a spindle unit driving apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a schematic configuration of the machine tool according to the first embodiment.
The machine tool 100 is an apparatus that moves a spindle unit 130 including a spindle 131 on which a replaceable tool 132 is mounted in three axis directions (XYZ directions), and performs various machining processes on the workpiece 10 using the tool 132. is there. As shown in FIG. 1, the machine tool 100 includes a base 110, a stage 120 provided on the base 110, a pair of columns 111 provided on the base 110, a beam 112 provided on the column 111, a beam 112, a slider 113 provided on the slider 112, a spindle unit 130 provided on the slider 113, a unit moving unit 200 that moves the spindle unit 130 relative to the workpiece 10, and a numerical control device that controls driving of the machine tool 100. 300 (see FIG. 2).
In the present embodiment, the machine tool 100 is exemplified by an apparatus having a portal structure in which the spindle unit 130 is movable relative to the workpiece 10 in three axial directions (XYZ directions). An apparatus having a configuration in which the spindle unit 130 is relatively moved in only one direction with respect to the workpiece 10 or a configuration in which the spindle unit 130 is moved in a two-dimensional direction (two directions) may be employed.

The base 110 is a pedestal on which a stage 120 and a column 111 are provided, and is fixed so as not to be moved when the workpiece 10 is processed.
The pair of columns 111 is erected with respect to the base 110, and a beam 112 is installed horizontally (along the Y direction) between the distal ends of the pair of columns 111. The beam 112 includes a guide rail 212Y along the Y direction, and a slider 113 is held on the guide rail 212Y so as to be movable along the Y direction. The slider 113 includes a guide rail (not shown) along the Z direction inside, and the spindle unit 130 is held on the guide rail so as to be movable along the Z direction. The stage 120 is a part on which the workpiece 10 is placed, and is provided on a guide rail 212X laid on the base 110 along the X direction so as to be movable along the X direction.

  The spindle unit 130 includes a tool 132 for machining the workpiece 10, a spindle 131 to which the tool 132 can be attached, and a spindle drive motor 133 (see FIG. 2) that drives the spindle 131 to rotate about the axis. ing. As the tool 132 for processing the workpiece 10, for example, any tool capable of processing the workpiece 10 by rotating the spindle, such as a drill for drilling a workpiece 10 or a friction stirring tool for friction stir welding the workpiece 10 Can be used.

The unit moving unit 200 includes an X-axis moving mechanism 210X, a Y-axis moving mechanism 210Y, and a Z-axis moving mechanism 210Z.
The X-axis movement mechanism 210X includes an X-axis motor 211X (see FIG. 2), and moves the stage 120 in the X direction along the guide rail 212X by the driving force of the X-axis motor 211X. The Y-axis moving mechanism 210Y includes a Y-axis motor 211Y (see FIG. 2), and moves the slider 113 along the guide rail 212Y along the Y direction by the driving force of the Y-axis motor 211Y. The Z-axis moving mechanism 210Z includes a Z-axis motor 211Z (see FIG. 2), and the spindle unit 130 is moved along the Z direction along the guide rail provided in the slider 113 by the driving force of the Z-axis motor 211Z. To move.
Each of the shaft motors 211 (211X, 211Y, 211Z) is driven at a predetermined drive speed based on a control signal output from the numerical control device 300, and the spindle unit 130 moves relative to the workpiece 10.
Each axis motor 211 (211X, 211Y, 211Z) is provided with a torque sensor 220 (X-axis torque sensor 220X, Y-axis torque sensor 220Y, Z-axis torque sensor 220Z) which is a torque detection unit of the present invention. The torque relating to the motor shaft of each shaft motor 211 is detected. The detected torque detected by each torque sensor 220 is output to the numerical controller 300. That is, each torque sensor 220 is connected to the numerical control device 300, and a detection signal output from the torque sensor 220 is input to the numerical control device 300.

The numerical controller 300 performs so-called computerized numerical control (CNC) in which the amount of movement of the spindle unit 130 and the rotational speed of the tool 132 in the machine tool 100 are numerically controlled by a computer. As such a numerical controller 300, a so-called PLC (programmable logic controller) that controls the machine tool 100 using a programming language (eg, G language) in which a relay circuit is symbolized can be employed. . The numerical control device 300 is not limited to the PLC as described above, and for example, a general-purpose personal computer may be used.
Specifically, as shown in FIG. 2, the numerical controller 300 includes a storage unit 310, an X-axis drive unit 320X, a Y-axis drive unit 320Y, a Z-axis drive unit 320Z, a main-axis drive unit 330, and a calculation unit 340. I have.

The storage unit 310 stores a machining program for controlling the machine tool 100 to perform machining on a workpiece, and various parameters for executing the machining program.
Various parameters stored in the storage unit 310 include a first torque limit value N ₁ that is a torque limit value for preventing damage according to the present invention, a second torque limit value N ₂ that is a torque limit value for promoting movement according to the present invention, The first time T ₁ which is the dead zone time for preventing damage according to the present invention, the second time T ₂ which is the review time for preventing damage according to the present invention, the third time T ₃ which is the dead zone time for promoting movement according to the present invention, The reference drive speed V _{S in} the motor 211, the speed fluctuation ratio m of each axis motor 211, flag information for speed return processing, and the like can be mentioned. Here, the first torque limit value N ₁ , the second torque limit value N ₂ , the first time T ₁ , the second time T ₂ , and the third time T ₃ are individually set for each shaft motor 211. Is set to Further, the reference driving speed V _S and the speed fluctuation ratio m may be set individually for each axis motor 211 or may be common to each axis motor 211. Furthermore, the drive speed of the spindle drive motor 133 may be stored as various parameters stored in the storage unit 310.
Here, the first torque limit value is an upper limit of a value that may cause damage to the spindle unit 130 or the unit moving unit 200 when the torque related to each shaft motor 211 exceeds the first torque limit value. Value. Therefore, it is possible to prevent the spindle unit 130 and the unit moving unit 200 from being damaged by driving each shaft motor 211 at a value equal to or less than the first torque limit value.
Further, the second torque limit value is a lower limit of a value that allows each axis motor 211 to be driven more quickly in order to perform the processing quickly because the torque related to each axis motor 211 is small. Value. Therefore, by driving each shaft motor 211 with a value equal to or greater than the second torque limit value, it is possible to perform a rapid machining process while preventing the spindle unit 130 and the unit moving unit 200 from being damaged. .
These various parameters can be appropriately set and input by the user, and can be changed, for example, when the machine tool 100 starts processing the workpiece 10.

  Each axis drive unit 320 (320X, 320Y, 320Z) is a drive circuit for driving each axis motor 211 (211X, 211Y, 211Z) at a predetermined drive speed. Each axis drive unit 320 sets and outputs a drive voltage for each axis motor 211 based on the speed command signal input from the calculation unit 340. Thereby, each axis motor 211 is driven at a speed according to the speed command signal, and the feed speed of the spindle unit 130 is set.

  The spindle driving unit 330 is a driving circuit for driving the spindle unit 130 at a predetermined driving speed. The spindle drive unit 330 sets and outputs a drive voltage (pulse signal) for the spindle drive motor 133 based on the machining command signal input from the calculation unit 340. As a result, the spindle drive motor 133 of the spindle unit 130 rotates at a speed based on the machining command signal, and the spindle 131 and the tool 132 attached to the spindle 131 rotate to process the workpiece 10.

The computing unit 340 is configured by an integrated circuit such as a CPU (Central Processing Unit) or a storage circuit, and executes a program read from the storage unit 310. Thereby, the calculating part 340 functions as the torque monitoring means 341, the process execution means 342, and the time measuring means 343, as shown in FIG.
The torque monitoring means 341 constitutes the torque comparison means of the present invention, and acquires the torque (detected torque) applied to each shaft motor 211 from the detection signal input from each torque sensor 220 (220X, 220Y, 220Z). To do. Further, the torque monitoring unit 341 reads the first torque limit value N ₁ and the second torque limit value N ₂ from the storage unit 310 and compares them with the detected torque N, and detects the detected torque N and the first torque limit value N ₁ . magnitude relationship, judges their magnitude relationship between the detected torque N and the second torque limiting value N _2.

The machining execution unit 342 reads a machining program from the storage unit 310 and performs a machining process for machining the workpiece 10. Specifically, the machining execution unit 342 has functions of a speed control unit 342A and a spindle control unit 342B.
The speed control means 342A determines the drive speed V of each axis motor 211 and outputs a speed command signal to each axis drive unit 320. Thereby, each axis drive part 320 outputs a control signal to each axis motor 211 based on a speed command signal, and drives it.
The speed control means 342A is the torque monitoring means 341, when the detected torque N is determined to exceed the first torque limit value N _1, the driving speed V of the shaft motor 211 in which the detected torque N is detected Process to reduce. At this time, the speed control unit 342A reads the first time T ₁ , the second time T ₂ , the reference drive speed V _S , and the speed fluctuation ratio m from the storage unit 310. Then, the speed control unit 342A is between the detected torque N exceeds the first torque limit value N ₁ timing to the first time T ₁ is passed, the detected torque N exceeds the first torque limit value N ₁ or when there until the driving speed V of the shaft motor 211 decelerates only the speed variation ratio m of the reference driving speed V _S. Further, it is driven at a speed and the reduced V timing, still if the detected torque N exceeds a first torque limit value N _1, further second time T ₂ is between detected torque N until the elapsed first torque limit value N If it remains above ₁ , the driving speed V of the shaft motor 211 is reduced by the speed fluctuation ratio m of the reference driving speed V _S. Thereafter, the speed control unit 342A until the detected torque N is first torque limit value N ₁ below, to implement the process of reducing the driving speed V.
Here, when the drive speed V becomes equal to or lower than the preset minimum drive speed _Vmin , the reduction process of the drive speed V higher than that may be stopped. In this case, the process of emergency stopping the machine tool 100 You may do.

Furthermore, when the drive speed V is reduced, the speed control unit 342A reads flag information for speed return processing indicating whether or not the drive speed V is returned to the original speed. Here, when a flag indicating that the speed return process is permitted is stored in the flag information, the speed control unit 342A performs the speed return process. Specifically, the speed control means 342A, when the detected torque N by the torque monitoring means 341 is determined to lower than the second torque limiting value N _2, the driving speed of the shaft motor 211 in which the detected torque N is detected V Execute the process to raise. At this time, the speed control unit 342A reads the third time T ₃ , the reference drive speed V _S , and the speed fluctuation ratio m from the storage unit 310, and the third time from the timing when the detected torque N falls below the second torque limit value N ₂ . until time T ₃ has elapsed, when the detected torque N remains below the second torque limit value N _2, the driving speed V of the axis motor 211, only the speed variation ratio m of the reference driving speed V _S Raise. Thereafter, the speed control unit 342A until the detected torque N is a second torque limiting value N ₂ or more, carries out a process of increasing the driving speed V.

The spindle control means 342B performs processing for determining whether to drive the spindle drive motor 133 on and off, and determining the rotational drive speed of the spindle drive motor 133. That is, the spindle control unit 342B rotates the spindle drive motor 133 at a constant drive speed at the timing when the spindle unit 130 is moved onto the workpiece 10 based on the machining program and various parameters read from the storage unit 310. . Further, when the spindle control means 342B determines that the machining has been completed based on the torque detected by each torque sensor 220, the spindle control means 342B performs a process of stopping the driving of the spindle drive motor 133.
Time measuring means 343 monitors have been not shown in the internal timer incorporated in the machine tool 100, the elapsed time from the timing when the detected torque N exceeds the first torque limit value N _1, reduced the driving speed V Timing And the elapsed time from the timing when the detected torque N falls below the second torque limit value N ₂ are counted.

[Machine tool operation]
Next, the operation of the machine tool 100 as described above will be described with reference to the drawings.
FIG. 3 is a flowchart showing the operation of the machine tool 100. FIG. 4 is a diagram illustrating a change in the torque related to the Z-axis motor and a change in the driving speed V of the Z-axis motor when the machine tool 100 according to the present embodiment drills the workpiece 10.
When the machine tool 100 according to the present embodiment performs a machining process for machining the workpiece 10, the numerical control device 300 performs various processes according to a procedure as shown in FIG. That is, when the user sets the execution of the processing, the processing execution unit 342 reads the processing program from the storage unit 310 and activates it. Thereby, the process execution means 342 performs the initial setting in the process (step S1). That is, the machining execution unit 342 reads the reference drive speed V _S of each axis motor 211 from the storage unit 310 and sets it as the drive speed V of each axis motor 211. Further, the machining execution means 342 initializes a change number counter i indicating the number of times the speed is changed, and sets “i = 0”. Further, the machining execution means 342 initializes a counter value T indicating an elapsed time to be counted when the detected torque N exceeds the limit value, and sets “T = 0”. Furthermore, the first torque limit value N ₁ , the second torque limit value N ₂ , the first time T ₁ , the second time T ₂ , which are various parameters required when the speed is changed by the speed control unit 342A. The third time T ₃ , the speed fluctuation ratio m, flag information indicating whether or not to perform speed return processing, and the driving speed of the spindle drive motor 133 are read.

Then, the machining execution unit 342 drives the machine tool 100 according to the machining program. That is, the speed control means 342A drives each axis motor 211 at the set drive speed V to move the spindle unit 130 to the machining part of the workpiece 10, and the spindle control means 342B drives the spindle drive motor 133. Then, the workpiece 10 is processed.
At this time, the torque monitoring unit 341 monitors the detected torque N related to each shaft motor 211 from the detected torque input from each torque sensor 220. Then, the torque monitoring unit 341 performs the comparing step detecting torque N determines whether exceeds the first torque limit value N ₁ (step S2).

In this step S2, when the detected torque N by the torque monitoring means 341 it is determined to have exceeded the first torque limit value N _1, the speed control unit 342A of the processing execution unit 342 performs the speed control step.
In this speed control step, the speed control means 342A first determines whether or not the counter value T is 0 (step S3). In step S3, the counter value T is, when a "T = 0", the timer means 343 starts to count the time elapsed from the detected torque N exceeds the first torque limit value N ₁ timing (step S4).

After step S4 or when it is determined in step S3 that the counter value T is not 0, the speed control means 342A determines whether or not the drive speed V is equal to or less than a preset minimum drive speed _Vmin. (Step S5). In step S5, when the driving speed V is below the minimum driving speed _{V min,} the process returns to step S2. When the driving speed V is equal to or lower than the minimum driving speed _Vmin , it may be determined that there is an abnormality in the unit moving unit 200 or the spindle unit 130 and the machine tool 100 may be subjected to an emergency stop.

Then, in step S5, the driving speed V is greater than a minimum driving speed _{V min,} the speed control unit 342A further change frequency counter i is equal to or a i ≧ 1 (step S6). In this step S6, when the change count counter i is i = 0, i.e., as shown in the timing A ₁ shown in FIG. 4, the driving velocity V is set reference driving speed V _S as the initial speed, the detected torque in the case where N is greater than the first first torque limit value N _1, the speed control unit 342A determines whether or not the first time T ₁ is elapsed (step S7). In step S7, the counter value T may first hour T ₁ less than, the flow returns to step S2, and continues the torque monitoring by the torque monitoring means 341.
In step S6, when the change number counter i is i ≧ 1, that is, when the drive speed V is reduced once or more as shown in the timings A ₂ and A ₃ shown in FIG. 4, the speed control is performed. It means 342A determines whether or not the second time _{T 2} has elapsed (step S8). In step S8, the counter value T is the second case h T ₂ less than, the flow returns to step S2, and continues the torque monitoring by the torque monitoring means 341.

Then, in step S7, if the counter value T is first time above T _1, or in step S8, if the counter value T is the second time T ₂ or more, the speed control unit 342A may reduce the driving speed V (Step S9).
At this time, the speed control unit 342A performs a process (V = V−V _S × m) for reducing the drive speed V by the speed fluctuation ratio m of the reference drive speed V _S. Here, as the speed fluctuation ratio m, for example, 10% or the like can be set.
Thereafter, the machining execution means 342 increments the change count counter i by 1 (step S10), initializes the counter value T, and sets it to 0 (step S11). Thereafter, the process returns to step S2, and the torque monitoring by the torque monitoring means 341 is continued.

In step S 2, when the torque monitoring unit 341 determines that the detected torque N is equal to or less than the first torque limit value N ₁ , the machining execution unit 342 uses the speed return process flag information read from the storage unit 310. Then, it is determined whether or not information indicating that the speed return is permitted is recorded, that is, whether or not the speed return is valid (step S12).
In step S12, when flag information indicating that the speed return is not permitted is recorded, the machining execution unit 342 does not perform the speed return process. In this case, the process execution unit 342 determines whether to continue the process (step S21). For example, when the user inputs that the machining process is to be terminated, the machining process performed by the series of machine tools 100 is terminated. If the process is not terminated in step S21, the process returns to step S2 and torque monitoring by the torque monitoring unit 341 is continued.

On the other hand, when flag information indicating that the speed return is permitted is recorded in step S12, the machining execution unit 342 performs a speed return process.
In this speed return process, the machining execution means 342 first determines whether or not the drive speed V is smaller than the reference drive speed V _S (step S13). In step S13, when the drive speed V is equal to or higher than the reference drive speed V _S , the process of step S21 is performed on the assumption that there is no need to return the speed.
If it is determined in step S13 that the drive speed V is lower than the reference drive speed V _S, it is determined by torque monitoring by the torque monitoring means 341 whether or not the detected torque N is below the second torque limit value N ₂ ( Step S14).
Fear In this step S14, if the detected torque N is the second torque limiting value N ₂ or more, increasing the driving speed V, the spindle unit 130 detects torque N exceeds the first torque limit value N ₁ is damaged Therefore, the driving speed V is not increased. In this case, the process proceeds to step S21.
On the other hand, in step S14, if the detected torque N by the torque monitoring means 341 is determined to be below the second torque limit value N _2, the speed control unit 342A, first determines whether the counter value T is 0 (Step S15). In step S15, the counter value T is, when a "T = 0", the clock means 343, elapsed from the timing when the detected torque N is below the second torque limit value N ₂ (timing A ₄ in FIG. ₄₎ Time counting is started (step S16).

After step S16, or in step S15, if the counter value T is determined not to be 0, the speed control unit 342A determines whether the third time _{T 3} has elapsed (step S17). In step S7, the counter value T may third time _{T 3} smaller, the process returns to step S14, and continues the torque monitoring by the torque monitoring means 341.
Further, in step S17, if the counter value T has become the third hour _{T 3} or more, the speed control unit 342A, the processing for increasing (restoring) the driving speed V (step S18). At this time, the speed control means 342A performs a process (V = V + V _S × m) for increasing the drive speed V by the speed fluctuation ratio m of the reference drive speed V _S. Here, as the speed fluctuation ratio m, the same value as in step S9 may be used, for example, 10% or the like may be set, or a different ratio may be set separately. Thus, the speed recovery process is performed.

Further, after this step S18, the speed control means 342A determines whether or not the driving speed V is equal to or higher than the reference driving speed V _S (step S19). If it is determined in step S19 that the driving speed V is equal to or higher than the reference driving speed V _S , the speed control unit 342A initializes the change count counter i, sets i = 0, and then executes step S21. To do. If it is determined in step S19 that the drive speed V is lower than the reference drive speed V _S , the process proceeds to step S21 as it is.
As described above, the machining process and the torque control process of the workpiece 10 by the machine tool 100 are performed.

[Operational effects of this embodiment]
As described above, the machine tool 100 according to this embodiment includes the spindle 131 on which the tool 132 is mounted, the spindle unit 130 including the spindle drive motor 133 that rotationally drives the spindle 131, and the spindle unit 130 in each of XYZ. A unit moving unit 200 that moves in the axial direction is provided, and each shaft motor 211 in the unit moving unit 200 is provided with a torque sensor 220. The numerical controller 300 that controls the driving of the machine tool 100 includes a torque monitoring unit 341 and a machining execution unit 342 having a speed control unit 342A. Torque monitoring means 341, the detected torque N detected in the torque sensor 220, it is determined whether or not exceeds the first torque limit value N _1, the speed control unit 342A, the detection torque N by the torque monitoring means 341 first If it is determined that the exceeding one torque limit value N _1, and carries out a process of reducing the driving speed V of the shaft motor 211 in which the detected torque N is detected. For this reason, before the load concerning the main shaft unit 130 breaks beyond the limit, the driving speed V of the shaft motor 211 can be reduced to reduce the load on the main shaft unit 130, thereby effectively preventing the main shaft unit 130 from being damaged. can do.

The speed control unit 342A at a timing detected torque N is the first time T ₁ from the time that exceeds the first torque limit value N ₁ has elapsed, to reduce the driving speed V. By providing such a dead zone time, it is possible to suppress a decrease in work efficiency. For example only temporarily detected torque N is increased, it wants if relatively quickly detected torque N is returned to the first torque limiting value N ₁ below. Even in such a case, if the driving speed V is reduced, the working efficiency is lowered. On the contrary, by providing the first hour T ₁ is a dead zone time, it is possible to suppress the deterioration of such work efficiency.

Furthermore, the speed control unit 342A, after reducing the driving speed V, still detected torque N if it exceeds the first torque limit value N _1, the timing of reducing the driving speed V is the second time T ₂ has elapsed At the timing, the driving speed V is further reduced. This ensures that the detected torque N is can be set to a stable driving state in which the first torque limit value N ₁ or less, it is possible to prevent damage to the spindle unit 130 more securely.

Further, the speed control means 342A reduces the driving speed V by the speed fluctuation ratio m of the reference driving speed V _{S in} the speed limiting step. For this reason, it is possible to suppress a decrease in work efficiency due to an excessive decrease in the drive speed V, and to move the spindle unit 130 relative to the workpiece 10 at the optimum drive speed V so as to continue the machining work efficiently. it can.

The storage unit 310 stores flag information for speed recovery processing, and information for permitting the speed recovery processing is recorded in the flag information, and the detected torque N is greater than the second torque limit value N ₂ by the storage unit 310. If it is determined that the speed is lower, the speed control means 342A performs a speed return process for increasing the drive speed V and returning it to approach the original speed. For this reason, when the load concerning the spindle unit 130 is small, the speed can be increased and the efficiency of the machining operation can be improved.

The speed control unit 342A, at the speed return processing, the detected torque N raises the driving speed V at the timing when the second time T ₂ has elapsed from the timing that falls below the second torque limit value N _2. By providing such a dead zone time, it is possible to avoid the inconvenience that the spindle unit 130 is overloaded at the time of speed recovery, and a stable machining operation can be performed.
Further, the speed control means 342A increases the drive speed V by the speed fluctuation ratio m of the reference drive speed V _S even during the speed return process. As a result, an increase in the load on the spindle unit 130 due to an excessive increase in the drive speed V can be suppressed, and an efficient machining operation can be performed by setting the feed speed of the spindle unit 130 at the optimum drive speed V.

Further, when the drive speed V by the speed control means 342A is changed, the reference speed is set as the reference drive speed V _S, and the drive speed V is changed by the speed change ratio m of the reference drive speed V _S. In this way, by using the reference drive speed V _S as a reference, the drive speed V can be varied by a constant speed, and stable speed management can be performed.

[Other Embodiments]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

For example, in the above embodiment, the number of times of varying the driving speed V from the reference driving speed V _S is the initial velocity and change frequency counter i, not limited to this. For example, when the detected torque N exceeds the first torque limit value N _1, the number may be a number of changes counter i with varying speed continuously. In this case, after being performed the speed limiting process by the speed control unit 342A, at the timing when the detected torque N is determined at the first torque limiting value N ₁ or less at step S2, the change frequency counter i is initialized i = It is sufficient to set 0.

When the speed is reduced by the speed control means 342A, the drive speed V is reduced by the speed fluctuation ratio m with respect to the reference drive speed V _S , and the relative movement speed serving as the reference of the present invention is set as the reference drive speed V _S. However, it is not limited to this. For example, the relative movement speed that is the reference of the present invention may be the driving speed V before the speed reduction. In this case, in step S9, the speed control means 342A may set a new drive speed V as “V = V−V × m”. In such a case, the speed reduction width becomes smaller as the speed is lowered. Therefore, an excessive decrease of the driving speed V is suppressed more reliably, while suppressing the torque of each axis motor 211 to the first torque limiting value N ₁ or less, it is possible to maintain the working efficiency.

The speed control means 342A sets the time until the drive speed V is reduced to either the first time T ₁ or the second time T _{2 according} to the change count counter i. It not, always treated to reduce the driving speed V at the timing when the T = T ₁ may be implemented. That is, T ₂ = T ₁ may be set.
Furthermore, although the first time T ₁ , the second time T ₂ , and the third time T ₃ until the drive speed V is changed are set, the dead zone time and the review time may not be set. In other words, the speed control unit 342A may reduce the driving speed V at the timing when the detected torque N exceeds the first torque limit value N _1, the detected torque N is the driving speed V at the timing when below the second torque limit value N ₂ You may perform the process which raises.

  In the above embodiment, the main shaft unit 130 is moved in the three axial directions. For example, the present invention is applied to the thrust direction (XY direction) in which the load on the main shaft is most concerned. It is good also as a structure which reduces the torque which concerns on a direction.

  In addition, the specific structure and procedure for carrying out the present invention can be appropriately changed to other structures and the like within a range in which the object of the present invention can be achieved.

  The present invention can be applied to a spindle unit driving device that controls driving when a spindle unit that holds a spindle is moved in a predetermined direction, and a driving method of the spindle unit driving device.

DESCRIPTION OF SYMBOLS 10 ... Work, 100 ... Machine tool (spindle unit drive device), 130 ... Spindle unit, 131 ... Spindle, 132 ... Tool, 133 ... Spindle drive motor (spindle drive part), 200 ... Unit moving part, 220 ... Torque sensor ( (Torque detection unit), 300 ... numerical control device (control unit), 310 ... storage unit (storage unit), 341 ... torque monitoring unit (torque comparison unit), 342A ... speed control unit, N ... detected torque, N ₁ ... first One torque limit value (damage prevention torque limit value), N ₂ ... second torque limit value (movement promotion torque limit value), T ₁ ... first time (damage prevention dead zone time), T ₂ ... second time (Review time for preventing breakage), T ₃ ... Third time (dead zone time for promoting movement).

Claims (8)

A main spindle unit including a main spindle on which a tool for machining a workpiece is mounted, and a main spindle driving unit that rotationally drives the main spindle;
A unit moving unit that moves the spindle unit relative to the workpiece;
A torque detector for detecting torque applied to the unit moving unit;
A control unit that controls a relative movement speed of the spindle unit with respect to the workpiece based on the detected torque detected by the torque detection unit;
The controller is
Storage means for storing a torque limit value for preventing breakage for preventing breakage of the spindle unit;
Torque comparison means for comparing the detected torque and the torque limit value for preventing damage;
Speed control means for reducing the relative movement speed of the spindle unit with respect to the workpiece by the unit moving section when the detected torque exceeds the breakage preventing torque limit value;
A spindle unit driving device comprising: The spindle unit driving apparatus according to claim 1,
The control unit includes time measuring means for measuring time,
The speed control means keeps the detected torque exceeding the breakage prevention torque limit value for a predetermined breakage prevention dead band time from the timing when the detected torque exceeds the breakage prevention torque limit value. In some cases, the spindle unit driving device is characterized in that the relative movement speed is reduced after the dead zone time for preventing breakage has elapsed. In the spindle unit driving device according to claim 2,
The speed control means, when the detected torque remains above the damage prevention torque limit value from the time when the relative movement speed is reduced until a predetermined breakage prevention review time elapses, The spindle unit drive device further reduces the relative movement speed after the breakage prevention review time has elapsed from the timing when the relative movement speed is reduced. In the spindle unit drive device according to any one of claims 1 to 3,
The spindle unit driving apparatus, wherein the speed control means reduces the relative movement speed at a constant ratio with respect to a reference relative movement speed. In the spindle unit drive device according to any one of claims 1 to 4,
The storage means stores a movement promoting torque limit value for urging movement of the spindle unit,
The spindle unit driving apparatus, wherein the speed control means increases the relative movement speed when the detected torque is lower than the movement promotion torque limit value. In the spindle unit drive device according to claim 5,
The control unit includes time measuring means for measuring time,
The speed control means keeps the detected torque below the movement promotion torque limit value while a predetermined movement promotion dead zone time elapses from the timing when the detected torque falls below the movement promotion torque limit value. In this case, the spindle unit driving apparatus is characterized in that the relative movement speed is increased after the dead zone time for movement promotion has elapsed. The spindle unit driving device according to any one of claims 4 to 6,
The spindle unit driving apparatus, wherein the speed control means increases the relative movement speed at a constant ratio with respect to a reference relative movement speed. A spindle equipped with a tool for machining a workpiece, a spindle unit including a spindle driving unit that rotationally drives the spindle, a unit moving unit that moves the spindle unit relative to the workpiece, and a unit moving unit. A spindle unit driving method for controlling a moving speed of the spindle unit in the unit moving unit based on the detected torque detected by the torque detecting unit,
A comparison step of comparing the torque limit value for preventing breakage for preventing breakage of the spindle unit and the detected torque;
A speed control step of reducing a relative moving speed of the spindle unit with respect to the workpiece by the unit moving unit when the detected torque exceeds the breakage preventing torque limit value in the comparing step;
A spindle unit driving method characterized by comprising:

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